Pipelines are an integral part of industry, and are widely used in refineries, power plants and other industrial applications. Pipelines, particularly pipelines used in these applications, deteriorate over time, causing a thinning of the pipe walls. Thinning of internal pipe walls can be caused by mechanical stress, flow assisted corrosion or erosion, chemical attack, water or electrochemical processes. In addition, moisture, such as from rain and snow, can be trapped between insulation placed around the periphery of the pipe and the outer surface of the pipe. The trapped moisture can corrode the pipe under the insulation, thereby causing a thinning of the external pipe walls. Thinning of the pipe walls can make the pipeline susceptible to leaking or rupturing, particularly when pressurized. Failure of the pipe wall, and the resultant leakage, can lead to facility downtime, require expensive repairs, and cause serious injury to workers and the environment.
Digital radiography has found wide application in industry for nondestructive testing of objects such as pipelines, welds, aircraft fuselages, turbine blades, rocket engines, and other composite structures. An exemplary system is described in our prior U.S. Pat. No. 6,925,145, the disclosure of which is hereby incorporated by reference herein.
In some cases, the scanning apparatus is stationed at a fixed location, and the objects to be tested are moved to the scanner and rotated to provide the necessary scanning views. One disadvantage of such systems is that it is often necessary to dismantle the object under test so that the parts can be moved to a fixed facility for inspection. In other instances, mobile scanners have been provided for imaging large structures on-site, but such systems tend to be awkward due to their large size and heavy weight, and have generally failed to provide simple, reliable, and responsive drive and control systems for precisely positioning the scanning apparatus over a particular part of the object. Moreover, such known mobile systems typically require secondary support structures, such as scaffolding, to support personnel access.
Therefore, there is a strong need to provide a reliable and maneuverable mobile scanning apparatus which is capable of maneuvering around awkward, hard-to-reach places to provide the necessary scanning views, and which is capable of precise positioning of the imaging payload over the object under test. It would also be desirable to provide a scanning apparatus which can be operated remotely so as to eliminate the need for secondary support infrastructure at the specific location the imaging is taking place, and to permit fine positioning of the apparatus from a remote stand-off position when the radiation source is producing radiation. Accordingly, it would be desirable if the deployed radiation detector is able to transmit a digital image via a communication network system over a distance away from the object under test. These and other advantages of the present invention will become apparent upon reading the following detailed description, accompanying drawings, and appended claims.